A number of metallic elements and some metallic alloys are well known to form tough metallic oxide liquids including water. These oxide coatings are highly stable and provide the metals and alloys with very high corrosion resistance. Examples of elemental metals on which native oxides are formed by exposure to air include aluminum, molybdenum, niobium, tantalum, titanium, tungsten, and zirconium. Tough oxide coatings are also formed on some stainless steel alloys, such as 316 stainless steel.
Although corrosion resistance is usually a highly desirable characteristic, the native oxides are usually electrically insulating. When the metals and alloys are used in electronic applications requiring the formation of an electrical contact to them, the oxides interfere with the formation of the contacts. If the oxides are removed by chemical treatment, such as etching with an acid or electrolytic etching, to expose the underlying metal, special steps must be taken in order to complete the electrical contacts before the native oxide can be regenerated and interfere with the electrical contacts. These measures require special apparatus and extremely careful handling of the materials. Therefore, they add to the cost of fabricating electronic components incorporating these corrosion resistant materials to which electrical contacts must be made.
It is, therefore, desirable to provide a process for making electrical contacts to metals and metal alloys on which a native oxide forms upon exposure of the metal or alloy to air and/or water.